Valve and method of assembling same

ABSTRACT

A valve having seats made of axially separable, inner and outer parts which may be moved to positions, during assembly of the valve, permitting adjacent parts of the valve body to be welded and the weldments to be stress relieved without damage to seal rings carried by the seats.

lllllllllw I United States Patent 1 [111 3,732,885 Allen [451 May 15, 1973 [54] VALVE AND METHOD OF 3,235,226 2/1966 Allen .251 315 x ASSEMBLING SAME 3,545,721 12/1970 Shafer ....25l/315 X 3,575,198 4/1971 Ellis ..137/315 [76] Inventor: Herbert Allen, PO. Box 1212, 3 2

Houston Tex 77001 ,666, 37 5/1972 Piccardo ..251/367 [22] Filed: Sept; 29, 1971 Primary Examiner-Harold yyjlleagey Mum [21 1 Appl No 184 727 Attrney Hger, Eckenobt, Thompson & Turner [57] ABSTRACT [52] US. Cl. ..l37/315, l37/246.22, 251/148, 1

251/174, 251/315, 251/316, 251/367 A valve having seats made of axially separable, inner s 1 Int. Cl ..F16k 27 10 and Outer Parts which may be moved to positions, 58 Field of Search ..137/315, 246.22; ing assembly of the valve, permitting adjacent parts of 251/148, 174, 315, 316, 367 the valve body to be welded and the weldments to be stress relieved without damage to seal rings carried by 6] References Cited the seats.

' UNITED STATES PATENTS 18 Claims, Drawing Figures 2,890,017 6/1959 Shafer ..251/367 X VALVE AND METHOD OF ASSEMBLING SAME This invention relates generally to valves. More particularly, it relates to improvements in valves of the type shown in U.S. Pat. No. 3,315,697, wherein separate parts of a central portion of the valve body are welded along their longitudinal edges to capture a closure member therein for rotation between open and closed positions and form a chamber about the closure having openings in each side. A seat is mounted within a tubular portion of the body which is joined by a girth weld to the central portion thereof in surrounding relation to each of the openings.

As shown in the aforementioned patent, a seal ring is carried on the inner end of the seat to engage the closure, and another seal ring is arranged between the outer diameter of the seat and the tubular body portion to seal between them. Since the seat extends through the side opening in the central body portion, the seal rings are in close proximity to the welds. Inasmuch as the heat radiating from the welding operations could ruin these seal rings, it has been proposed to circulate water around them during this time. I

However, not even this procedure is adequate to protect the seal rings from the higher and more sustained temperatures incurred in stress-relieving the weldment. Furthermore, due to the disposal of the seat across the inner side of the weldment, it has been difficult to X-ray the girth weld to'detect imperfections.

An object of this invention is to provide a valve of this type which may be assembled without the necessity of circulating coolant past the seal rings or other parts of the seats susceptible to damage during the welding operation.

Another object is to provide a valve of this type in which the weldments may be stress-relieved without damage to these seat parts.

A further object is to provide a valve of this type in which the girth weld may more readily be X-rayed.

Still another object is to provide a method of assembling a valve which enables one or more of the foregoing objects to be accomplished with a minimum of time, expense and effort. I

These and other objects are accomplished, in accordance with the illustrated embodiments of the invention, by a valve in which the seal rings or other parts of the seat susceptible to damage by the welding and related operations may, despite theircapture within the valve body, be arranged in positions within the valve body remote from the weld area during such operations and then, upon completion thereof, moved within the valve body to the positions they normally occupy near such area for engaging between the valve body and closure member. Thus, each seat comprises separable inner and outer annular parts, with the inner part normally engaging between the closure member and outer seat part and the outer'seat part normally engaging between the inner seat part and the tubular body portion. The closure member and central body portion are so spaced that the inner seat part, when separated from the outer seat part, may be arranged between them in its remote position and then moved between them to its normal position. The outer seat part is slidable longitudinally within a recess in the tubular portion so that, when separated, it may be arranged in its remote position by being slid away from the closure member and then slid back toward the closure member to its normal position.

The inner seat part may carry a seal ring on its inner end which engages the ball closure, and the outer part is axially slidably mounted within and sealed with respect to a recess in the tubular body portion by a seal ring arranged between them. The inner and outer seat parts are sealed with respect to one another by a seal ring between them, and the seat is yieldably urged against the closure by spring means preferably disposed in the recess outwardly of the seat. By virtue of this invention, these seal rings, as well as other portions of the seat btherwise subject to damage, are protected from the welding and related operations.

In one illustrative embodiment of the invention, wherein each opening from the chamber is smaller than the inner seat part, the inner seat part is arranged between the closure and the parts of the central body portion as the longitudinal edges of the latter are welded together. More particularly, in order to prevent damage to seal rings carried by the inner seat part, such part is arranged in a position remote from the weld and between the closure and the central body portions as they are welded together. The illustrated closure is a ball 7 which preferably has stems on its opposite ends rotatably journaled in the central body portion as its separate parts are connected together, and each inner seat part is intermediate the stems when arranged in such remote position.

In a second illustrative embodiment of the invention, each side opening is larger than the inner seat part so that the inner seat part may be moved therethrough subsequent to welding of the separate parts of the central body portion. However, in this embodiment as well as in the first embodiment, the inner seat part may be arranged, prior to the .welding of a tubular portion to the central body portion, in a position in which it is to one side of and thus remote from an opening in the chamber. In the case of the first embodiment, this requires movement of the inner seat part from its position during formation of the welds between the longitudinal edges of the central body portion. In the case of the second embodiment, the inner seat part may be moved directly into such position upon movement through a side opening.

With the inner seat part so displaced, the outer seat part is inserted into the outer end of a recess in the tubular body portion, and thus to a position remote from the area to be welded to the central body portion. The tubular portion is then welded to the central body portion and the weld is heat-treated and X-rayed. If a similar structure is to be welded to the opposite side of the central body portion, there will have been two inner seat parts displaced for the first girth weld and then repositioned for the second.

The outer seat part is then moved inwardly to permit insertion of the seal ring for sealing between the seat and the recess, whereupon the inner and outer seat parts are moved to assembled position and the spring means inserted into operative position within the recess for yieldably urging the seat parts together, and thus the inner seat part against the ball closure.

Preferably, the inner seat part includes a seal ring for sealing between the inner and outer seat parts so that, when the inner seat part of the first embodiment is in its position remote from the welding of the longitudinal edges of the central body portion, it is removed from the heat thereof. Also, when the inner seat part of either embodiment is positioned to one side ofthe chamber opening, they are removed from the heat of the girth welding and stress-relieving operations.

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is a side view, partlyv in section, of a ball valve I assembled in accordance with the first-mentioned embroken line 3-3 of FIG. 2, showing the longitudinal edges welded'and the inner seat parts moved to positions preparatory to formation of one of the girth welds;

FIG. 4 is a sectional view of the valve as seen along broken line 44 of FIG. 3, during formation of such girth weld;

FIG. 5 is an enlarged sectional view of a portion of the valve of FIGS. 1 to 4, with the outer seat part moved inwardly from its position in FIG. 4 and the seal rings inserted into a groove within the recess in the tubular body portion; I

FIG. 6 is a view similar to FIG. 5, but with the assembly of the valve completed;

FIG. 7 is a perspective view of'apart of the spring means;

FIG. 8 is an enlarged sectional view a part a portion of a valve during assembly in accordance with the second-mentioned embodiment of the invention, wherein the inner seat part has been moved through the chamber opening and into a position remote from the area thereabout to be welded;

FIG. 9 is a view similar to FIG. 8, but upon completion of the weld and movement of the outer seat part inwardly to facilitate installation of seal rings; and

FIG. 10 is a view similar to FIG. 9, but with the assembly of the valve completed.

With reference now to the details of the abovedescribed drawings, the valve made in accordance with the first embodiment of the invention, and indicated in its entirety in FIG. 1 by reference character 20, includes a valve body 21 having a flowway 22 therethrough, and a ball closure 23 having a port 24 therethrough and rotatably mounted within the valve body for selectively opening and closing the passage through the flowway. Theball closure is arranged concentrically within a spherically shaped chamber 25 intermediate the opposite cylindrical ends of the flowway and has upper and lower stems 26 and 27 journaled within bearings 26A and 27A formed in the valve body at the upper and lower sides of the chamber. The upper stem extends through a seal ring in the upper bearing and has an exterior end to which a suitable operator (not shown) may be connected for rotating the ball closure.

An annular seat 28 is slidably mounted within an annular recess 29 at each intersection of flowway 22 with chamber 25. The inner end of each seat sealably engages the ball closure, and the outer diameter of a portion of each seat is sealably slidable within its recess 29. The inner diameter of the seat forms a continuation of flowway 22. The rightand left-hand sides of the valve may be identical.

Chamber 25 is formed within a central body portion comprising upper and lower hemispherically shaped parts 31 and 32, respectively. The adjacent side edges of these parts are disposed generally longitudinally in a plane perpendicular to the axis of rotationof the ball closure, and are welded together, as indicated at 30, to mount stems 26 and 27 in bearings 26A and 27A, respectively. The connection of the parts also forms flowway openings 33 in oppositesides of the chamber. The diameter of openings 33 is less than the outer diameter of seat 28.

The valve body 20 also includes a pair of tubular portions 34 each having an inner end welded at 35 to an annular surface on the central body portion surrounding an opening 33 therein. Each seat 28 is axially slidably mounted within recess 29 extending axially outwardly from the inner end of one of the tubular portions, so that when the latter are so connected to the central body portion, the seats 28 are arranged to extend through the openings 33 and thus across the inner sides of the weldments 35.

As best shown in FIGS. 5 and 6, each seat 28 includes inner and outer, axially separable annular parts 36 and 37, interfitted so as to maintain them in axial alignment. The outer part is axially slidable within recess29 and spring means 50, in the recess behind the outer part, urges-both parts toward the ball closure. A seal ring 38 is carried on the inner end of inner seat part 36 for sealably engaging the ball closure, a pair of seal rings 42 and 43 are carried on the outer end of seat part 36 for sealably engaging the inner end of outer-seat part 37, and a pair of seal rings 39 in a groove 40 in recess 29 seals between outer seat part 37 and the recess.

The spaceS between the closure and chamber permits the inner part of each seat to be arranged in a posi tion to one side of opening 33, so that, as shown in FIG. 5, the outer seat part 37 may be moved axially within recess 29 to an innermost position in which it extends through opening 33 to engage the ball closure, as shown in FIG. 5. Prior to insertion of spring means 50, the outer seat part may be moved to an outer position (not shown) in which it is also within opening 33, but spaced from the ball closure a sufficient distance to permit the inner seat part 36 to be moved from its position of FIG. 5 into the position of FIG. 6 and thus into axial alignment with the outer seat part. More particularly, the outer seat part 37 may be moved axially outwardly to the position shown in FIG. 4, in which position its inner end is disposed axially outwardly from the seat part, and, when the seat parts are so interfitted,

they are sealed with respect to one another by the seal rings 42 and 43.

To assemble the valve, the inner seat parts 36 are placed between the ball closure and the upper and lower parts 31' and 32 of the central body portion as the latter. are moved into positions about the ball closure preparatory to welding one pair of longitudinal edges as at 30. As shown in FIG. 2, parts 36 are arranged in positions within the space S remote from each weldment, and thus in positions in which heat from the weldment will not damage the seal rings carried by the inner seat parts. The edges are welded by a torch T and the weldment may also be stress-relieved. Parts 36 are then moved to the other side of the closure and the other pair of longitudinal edges is welded.

Preparation is then made for welding a tubular body portion 34 to the central body portion about one of the openings 33 by a girth weld 35. The inner seat parts may be moved within the space S into the position shown in FIGS. 3, 4 and 5, which, in effect, involves turning one of them approximately 180 from the position it occupied during formation of a weld 30. An outer seat part 37 is inserted in the inner end of a tubular body portion which is then juxtaposed with the annular surface of the central body portions to which it is to be welded, as shown in FIG. 4. The outer seat part is preferably in its axially outermost position. A girth weld 35 is then formed, as by means of a welding torch T, and subsequently stress-relieved in any conventional manner. With the outer seat part in the position shown I in FIG. 4, the X-ray gun is able to take a clear picture of the weld 30 without interference with extraneous material cross its inner side. The other tubular body may be assembled in similar fashion.

Upon completion of welding-related operations, outer seat part 37 is moved inwardly to the position of FIG. 5, to uncover groove 40 in recess 29 and thus permit seal rings 39 to be inserted through the tubular body portion and into such'grooves. Seal rings 39 are resilient and may be collapsed for insertion through the tubular body portion. When so inserted, the seal rings are located for sealing between the tubular body portion and the outer seat part 37 when the latter is moved outwardly into the position of FIG. 6.

Lubricant from an external source is supplied to a groove 45 about the inner end of the seat radially inwardly of the seal ring 38. For this purpose, each of the inner and outer seat parts is provided with a series of ports 46 and 47, respectively, connecting the groove 45 in the inner seat part with the groove 40 in which the seal rings 39 are arranged. These seal rings are held apart by a coil spring 48 disposed between then so as to sealably engage the outer diameter of outer seat part 37 on opposite sides of the groove 47, and seal rings 42 and 43 are so mounted on the outer end of the inner seat part 36 as to seal between the inner seat part and outer seat part radially outwardly and inwardly, respectively, of the intersecting ports 46 and 47. Thus, lubricant fed from a suitable source through a port 49 in the tubular valve body portion is confined for flow into the groove 47 and thus into the groove 45. Of course, the coil spring 48 may be collapsed in much the same manner as the seal rings 39 to permit it to be inserted through the tubular body portion. With outer seat part 37 moved outwardly a sufficient distance, the inner seat part 36 is swung into the position of FIG. 6. Then the outer seat part is moved inwardly into interfitting relation therewith, as shown in FIG. 6, in which position seal rings 39 seal between the outer seat part and recess 29.

Spring means 50 is then inserted through the tubular body portion and into the recess 29 axially outwardly of the outer seat part. Several such springs are well known in the art. As illustrated, spring 50 comprises a plurality of spring segments 51 each comprising an arcuate arm having a button 52 at its opposite ends for engaging the outer end of the outer seat part, and a screw 53 threadedly carried intermediate the buttons. With all segments in place within the recess, the screws are extended to cause heads 54 to abut the end 41 of the recess and thus permit a desired force to be transmitted to the outer seat part.

The second embodiment of the invention is much like the first in that, as illustrated in part in FIGS. 8 to 10, it is also made up of a valve body having a central portion comprised of upper and lower parts connected together along adjacent longitudinal edges which lie generally within a plane perpendicular to the axis of rotation of a ball closure 56 and which form a chamber 57 in which the ball closure 56 is concentrically arranged and define openings 58 in opposite sides of the chamber. Also, the inner end of a tubular body portion 59 is welded at 60 to an annular surface of the tubular body portion surrounding each of the openings 58; and, after assembly of the valve (FIG. 10), a seat 61 is axially slidably mounted within a recess 59b extending outwardly from the inner end of the tubular body portion and having an outer end 74, so as to extend through the opening 58 and engage at its inner end the ball closure 56.

As in the first embodiment, the seat 61 includes an inner part 62 which is axially separable from and interfittable with an outer seat part 63. Inner seat part 62 carries a seal ring 64 on its inner side for sealably engaging the ball closure, and seal rings 65 and 66 on its outer end for sealably engaging the inner end of the outer seat part 63 when the seat parts are interfitted.

Seal rings 67 and 68 are arranged between the outer diameter of the outer seat part 63 and the recess 59b to form a seal therebetween. The last-mentioned seal rings are held apart by a spacer 69 so as to seal on opposite sides of a lubricant port 590 in the tubular body portion 59 and 63a in the outer seat part 63, and the seal rings 65 and 66 seal on opposite sides of port 63a and a port 62a in the inner seat part 62. Thus lubricant from an external source may be supplied to a groove 74a on the inner end of the inner seat part.

Spring means 70 is arranged within the recess 59b axially outwardly of the outer seat part 63 for urging the outer seat part and thus the inner seat part toward the ball closure 56. Spring means 70 also includes wavy spring segments 72 whose inner side engages the outer side of seal ring 68, and whose outer undulations are engaged by a segmented spring 73 similar to that shown at 50 in FIG. 6. Seal rings 67 and 68 are arranged on a reduced diameter portion 71 about the outer end of the outer seat part.

In this second embodiment of the invention, the openings 58 in the sides of the central body portion are larger than the outer diameters of inner seat parts 62, so that its not necessary to arrange the latter between the separate parts of such body portions as they are welded together. However, as in the first embodiment of the invention, in preparation for making girth weld 60, the inner part 62 of each seat is movable within annular space S between the closure member 56 and the wall of chamber 57. Thus, the inner seats may be moved through chamber opening 58 and arranged in the positions corresponding to those illustrated in FIG. 4. Thus seal rings 64, 65 and 66 carried thereon are remote from the heat of welding and stress-relieving.

The remaining assembly operations will be obvious from the description given of the first embodiment.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and method.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations.

' This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1. A valve, comprising a valve body, a closure member captured within the valve body, and a seat normally positioned to engage between the closure member and valve body and including a part captured within the valve body, said valve body including portions which are welded to one another in an area near the normal position of the seat, and said seat part being arrangeable in a position within the valve body which is remote from said area during welding of said portions and being movablewithin the valve body from said remote position to said normal position upon completion of said welding.

2. A valve of the character defined in claim 1, wherein said seat part includes a rigid body and a seal ring.

3. A valve of the character defined in claim 1, wherein the seat part is separable from the remainder of the seat to permit its arrangement in and movement from said position'remote from the weld area.

4. A valve, comprising a body having a central portion with a side opening therein and a tubular portion welded to the central portion about the side opening, a closure member captured within the valve body, and

a seat part captured within the valve body and includ-.

ing inner and outer separable parts normally positioned for engagement with one another and the closure member and tubular portion, respectively, one of said parts being arrangeable within said body, when separated from the other, in a position which is remote from the weld between the tubular and central body portions and being movable from said position and within said body into said normal position.

5. A valve of the character defined in claim 4, wherein said one part is the inner part which is arrangeable and movable between the closure member and central body portion.

6. A valve of the character defined in claim 4, wherein said one part is the outer part which is slidable within the tubular body portion between its remote and normal positions.

7. A ball valve, comprising a body including a central portion with separate parts connected together to form a side opening therein and including a tubular portion welded to the central portion about said opening, a ball closure rotatably mounted within the central body portion for opening and closing the valve, said tubular portion having an annular recess within its inner end, a seat comprising interfitting, separable inner and outer annular parts, said inner seat part engaging the ball closure and said outer seat part being axially slidable within said recess, said central body portion and ball closure being spaced apart to permit the inner seat part to be arranged about the ball closure in a position to one side of said opening, a seal ring between the outer seat part and the recess, and means yieldably urging the outer seat part against the inner seat part and the inner seat part against the ball closure, said seal ring and said urging means being insertable through the outer end of said tubular body portion.

8. A ball valve of the character defined in claim 7,

wherein said annular recess is sufficiently long to permit the outer seat part to be slid outwardly away from said weld during assembly.

9. A ball valve of the character defined in claim 7, wherein said opening is smaller than said inner seat part, the side edges of the separate parts of the central body portion are welded to one another along a plane generally transverse to the axis of rotation of the ball closure, and the spacing between the central body portion and ball closure permits the inner seat part to be arranged in a position on the side of the ball closure away from the side edges being welded.

10. A ball valve of the character defined in claim 7, wherein said opening is larger than said inner seat part.

11. A ball valve of the character defined in claim 7, wherein said inner seat part includes a seal ring for sealing between the inner and outer seat parts when said parts are interfitted and yieldably urged against one another.

12. A ball valve of thecharacter defined in claim 7, wherein there is an annular groove between the outer seat part and recess into which said seal ring is insertable.

13. A ball valve of the character defined in claim 12, wherein said groove is in the recess, and said outer seat part is axially shiftable to a position within the recess to permit the seal ring to be inserted into said groove.

14. A ball valve of the character defined in claim 13, wherein said outer seat part is inwardly shiftable toward the ball closure, upon arrangement of the inner seat part in its position to one side of said opening, to uncover said groove for insertion of said seal ring.

15. A ball valve of the character defined in claim 7, wherein there are stems on opposite ends of the ball closure rotatably journaled in said central body portion, and the first seat part is intermediate the stems when arranged in its position to one side of said openmg.

16. A ball valve, comprising a valve body including a central portion having separate parts connected together to form openings in the opposite sides thereof and including a pair of tubular portions each welded to the central portion about one of said openings, a ball closure mounted for opening and closing the valve, each said tubular portion having an annular recess within its inner end, a pair of seats each comprising interfitting, separable inner and outer annular parts, each said inner seat part engaging the ball closure and each said outer seat part being axially slidably mounted within one of said recesses, said central body portion and ball closure being spaced apart to permit each inner seat part, upon separation from the outer part, to be arranged about the ball closure in a position to one side of one opening, a seal ring between each outer seat part and its recess, and means yieldably urging each said outer part against an inner part and said inner part against the ball closure, said seal rings and said urging means being insertable through the outer ends of said tubular body portions.

17. A ball valve of the character defined in claim 16, wherein there are stems on opposite ends of the ball closure rotatably journaled in said central body portion, and each first seat part is intermediate the stems when arranged in said position to one side of one opening.

18. A ball valve of the character defined in claim 16, wherein each said inner seat part includes a seal ring for sealing between the inner and outer seat parts. 

1. A valve, comprising a valve body, a closure member captured within the valve body, and a seat normally positioned to engage between the closure member and valve body and including a part captured within the valve body, said valve body including portions which are welded to one another in an area near the normal position of the seat, and said seat part being arrangeable in a position within the valve body which is remote from said area during welding of said portions and being movable within the valve body from said remote position to said normal position upon completion of said welding.
 2. A valve of the character defined in claim 1, wherein said seat part includes a rigid body and a seal ring.
 3. A valve of the character defined in claim 1, wherein the seat part is separable from the remainder of the seat to permit its arrangement in and movement from said position remote from the weld area.
 4. A valve, comprising a body having a central portion with a side opening therein and a tubular portion welded to the central portion about the side opening, a closure member captured within the valve body, and a seat part captured within the valve body and including inner and outer separable parts normally positioned for engagement with one another and the closure member and tubular portion, respectively, one of said parts being arrangeable within said body, when separated from the other, in a position which is remote from the weld between the tubular and central body portions and being movable from said position and within said body into said normal position.
 5. A valve of the character defined in claim 4, wherein said one part is the inner part which is arrangeable and movable between the closure member and cenTral body portion.
 6. A valve of the character defined in claim 4, wherein said one part is the outer part which is slidable within the tubular body portion between its remote and normal positions.
 7. A ball valve, comprising a body including a central portion with separate parts connected together to form a side opening therein and including a tubular portion welded to the central portion about said opening, a ball closure rotatably mounted within the central body portion for opening and closing the valve, said tubular portion having an annular recess within its inner end, a seat comprising interfitting, separable inner and outer annular parts, said inner seat part engaging the ball closure and said outer seat part being axially slidable within said recess, said central body portion and ball closure being spaced apart to permit the inner seat part to be arranged about the ball closure in a position to one side of said opening, a seal ring between the outer seat part and the recess, and means yieldably urging the outer seat part against the inner seat part and the inner seat part against the ball closure, said seal ring and said urging means being insertable through the outer end of said tubular body portion.
 8. A ball valve of the character defined in claim 7, wherein said annular recess is sufficiently long to permit the outer seat part to be slid outwardly away from said weld during assembly.
 9. A ball valve of the character defined in claim 7, wherein said opening is smaller than said inner seat part, the side edges of the separate parts of the central body portion are welded to one another along a plane generally transverse to the axis of rotation of the ball closure, and the spacing between the central body portion and ball closure permits the inner seat part to be arranged in a position on the side of the ball closure away from the side edges being welded.
 10. A ball valve of the character defined in claim 7, wherein said opening is larger than said inner seat part.
 11. A ball valve of the character defined in claim 7, wherein said inner seat part includes a seal ring for sealing between the inner and outer seat parts when said parts are interfitted and yieldably urged against one another.
 12. A ball valve of the character defined in claim 7, wherein there is an annular groove between the outer seat part and recess into which said seal ring is insertable.
 13. A ball valve of the character defined in claim 12, wherein said groove is in the recess, and said outer seat part is axially shiftable to a position within the recess to permit the seal ring to be inserted into said groove.
 14. A ball valve of the character defined in claim 13, wherein said outer seat part is inwardly shiftable toward the ball closure, upon arrangement of the inner seat part in its position to one side of said opening, to uncover said groove for insertion of said seal ring.
 15. A ball valve of the character defined in claim 7, wherein there are stems on opposite ends of the ball closure rotatably journaled in said central body portion, and the first seat part is intermediate the stems when arranged in its position to one side of said opening.
 16. A ball valve, comprising a valve body including a central portion having separate parts connected together to form openings in the opposite sides thereof and including a pair of tubular portions each welded to the central portion about one of said openings, a ball closure mounted for opening and closing the valve, each said tubular portion having an annular recess within its inner end, a pair of seats each comprising interfitting, separable inner and outer annular parts, each said inner seat part engaging the ball closure and each said outer seat part being axially slidably mounted within one of said recesses, said central body portion and ball closure being spaced apart to permit each inner seat part, upon separation from the outer part, to be arranged about the ball closure in a position to one side of one opening, a seAl ring between each outer seat part and its recess, and means yieldably urging each said outer part against an inner part and said inner part against the ball closure, said seal rings and said urging means being insertable through the outer ends of said tubular body portions.
 17. A ball valve of the character defined in claim 16, wherein there are stems on opposite ends of the ball closure rotatably journaled in said central body portion, and each first seat part is intermediate the stems when arranged in said position to one side of one opening.
 18. A ball valve of the character defined in claim 16, wherein each said inner seat part includes a seal ring for sealing between the inner and outer seat parts. 